On/off and level control of controlled devices, e.g., lighting devices or other load devices, is often done with the same control element, e.g., a switch, whereby e.g. in case of a pushbutton switch a short push is used to request a state change (e.g., on/off/toggle), and a long push of the same pushbutton switch is used to request a level change (e.g., dim/move up/down or step up/down). Conventional mains- or battery-powered control elements (e.g., remote controls, switches, dimmers) can locally measure the press duration and depending the on the measured value send the appropriate control command(s), e.g., on/off/toggle in case of a short activation, and move up/down, followed by stop or repetitive step up/down in case of a longer activation.
Extremely resource-restricted, esp. energy-restricted control elements, incl. energy-harvesting control elements which harvest energy from the actuation, are emerging thanks to the introduction of e.g. EnOcean (as defined in the ISO/IEC 14543-3-10 specification) and ZigBee Green Power systems. Such control elements may not have enough energy to differentiate between short and long activation or detect a short activation. Thus, they typically would send commands indicating start of activation (e.g., press operation) and end of activation (e.g., release operation) separately (in the following referred to as “raw control commands”). The control action (in the following referred to as “derived control action”) can thus be determined by the receiver depending on the time interval between the received commands (of particular type).
However, in case of lighting applications or other network-based application, frequently more than one receiver (lamp/ballast) is controlled simultaneously by the same control element (e.g., switch or sensor or remote control), preferably using group communication (as e.g. defined in the ZigBee Light Link specification or ZigBee Green Power specification). The controlled devices may thus be located at different distances from the control element, e.g., several hops away, wherein a hop represents a link, i.e. one portion of the network path between source and destination. When communicating over a wireless mesh network, data passes through a number of intermediate devices (like routers or other network devices) rather than flowing directly over a single bus wire. Thus, the measured interval between the received commands will be influenced by the delay at the transmitting and receiving device, as well as in case of multi-hop systems all intermediate devices along the possibly different routing paths. Various aspects may contribute to this delay, including processing, channel access mechanisms, network/application quality of service (QoS) mechanisms like random jitter when multiple devices may be involved, interference and retry mechanisms, and delay on the receiving side (related to processing, other interrupts, etc.). Different intervals between the received raw control commands however, especially in case of multi-hop systems and group communication, will lead to different derived control actions, e.g., some devices in the group executing an on/off/toggle while some other devices executing dimming (to potentially differing levels).